Exhaust gas discharged from internal combustion engines of automobiles and the like contains particulate matter (PM) and harmful gases such as carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons (HC). An exhaust gas catalytic converter that decomposes such harmful gases is also referred to as a three-way catalytic converter. A common three-way catalytic converter includes a catalyst layer that is formed by wash-coating a honeycomb-shaped monolithic substrate made of cordierite or the like with slurry containing noble metal particles having catalytic activity.
Patent Literature 1 discloses a honeycomb structured body including a honeycomb fired body which is an extrudate containing ceria-zirconia composite oxide particles (hereinafter also referred to as “CZ particles) and alumina particles, wherein peaks in a pore size distribution curve are in ranges of 0.01 to 0.1 μm and 0.1 to 5 μm.